A [100 x 1] matrix (also called "column vector") has one element per row only. Therefore the sum over the elements of each row is exactly the same matrix. If you ask for the sum over the column, you are very near to the solution already. The standard method to solve such problems is to read the documentation. Type this in the command line:
docsearch sum
It will reveal, that the command for summing is called "sum". Now type:
help sum
doc sum
Here you find all you need.
The documentation contains some chapters called "Getting Started". It is recommended to read them, because a forum is not efficient for solving all the problems of beginners, when professionals have written these very good tutorial already.
PS. Welcome to the forum! While answers as this one are typical for the kind of politeness in this forum, "RTFM" and "plz"s are not liked. If you like to say "please" at all, better take the time to spell it correctly. If you really want to save some time, do not omit characters, but emotional claims like "it's ridiculous". They waste your and our time only and there is no reason to spend time to let a question look less serious.
